In-hospital and 30-day major adverse cardiac events in patients referred for ST-segment elevation myocardial infarction in Dhaka, Bangladesh

Abstract

Background: There is a paucity of data regarding acute phase (in-hospital and 30-day) major adverse cardiac events (MACE) following ST-segment elevation myocardial infarction (STEMI) in Bangladesh. This study aimed to document MACE during the acute phase post-STEMI to provide information.

Methods: We enrolled STEMI patients of the National Institute of Cardiovascular Disease, Dhaka, Bangladesh, from August 2017 to October 2018 and followed up through 30 days post-discharge for MACE, defined as the composite of total death, myocardial infarction, and coronary revascularization. Demographic information, cardiovascular risk factors, and clinical data were registered in a case report form. The Cox proportional hazard model was used for univariate and multivariate analysis to identify potential risk factors for MACE.

Results: A total of 601 patients, mean age 51.6±10.3 years, 93% male, were enrolled. The mean duration of hospital stay was 3.8±2.4 days. We found 37 patients (6.2%) to experience an in-hospital event, and 45 (7.5%) events occurred within the 30 days post-discharge. In univariate analysis, a significantly increased risk of developing 30-day MACE was observed in patients with more than 12 years of formal education, diabetes mellitus, or a previous diagnosis of heart failure. In a multivariate analysis, the risk of developing 30-day MACE was increased in patients with heart failure (hazard ratio = 4.65; 95% CI, 1.64–13.23).

Conclusions: A high risk of in-hospital and 30-day MACE in patients with STEMI exists in Bangladesh. Additional resources should be allocated providing guideline-recommended treatment for patients with myocardial infarction in Bangladesh.  

Background

Acute coronary syndrome is among the leading causes of morbidity and mortality globally [1], but, while the incidence and mortality rates are declining in most developed nations, they are on the rise in developing countries [2, 3]. The decline may be attributed to increased adherence to treatment guidelines and changes in lifestyle and behavior [4–7]. ST-segment elevation myocardial infarction (STEMI) is the most common acute manifestation of coronary artery disease [8], accounting for approximately one-third of acute coronary syndromes in both developed and developing countries [9, 10]. In economically disadvantaged areas like Bangladesh, the prevalence of coronary artery disease and STEMI remains mostly unknown, and only small scale epidemiological surveys provide evidence of its increase [11].

Myocardial infarction is two to three times more common in patients who have survived an earlier STEMI than in the general population[12]. Older age, no revascularization procedure, and comorbidities have been identified as significant risk factors for recurrence [12]. Most studies of post-STEMI outcomes focus on the acute phase, in-hospital and 30 days post-discharge, after the index event [13, 14]. A literature search produced only a single study from Bangladesh describing post-STEMI outcomes as a composite of major adverse cardiac events (MACE) in a rural setting [15].

In a resource-limited setting, it is not always feasible to adopt the best treatment strategies for the management of STEMI. Differences in epidemiological, as well as clinical factors, may contribute to greater risk of adverse events following STEMI [16, 17] that can potentially impact patient-specific outcomes [18]. This situation exists even in the large tertiary care cardiac hospital in the capital city of Dhaka, as STEMI patients referred from throughout Bangladesh receive treatment here. Bangladesh, with rapidly progressing urbanization, is undergoing a demographic and epidemiological transition from infectious diseases to non-communicable diseases as primary areas of concern [19, 20]. Common behavioural, metabolic, and physiological risk factors of coronary artery disease are prevalent in the Bangladesh population [21, 22]. In light of this transition, and considering the paucity of in-hospital and 30-day MACE data in urban locations in Bangladesh, we aimed to determine MACE rates in the acute phase post-STEMI for evidence-based guidance to inform the mobilization of resources for therapeutic strategies in STEMI.

Methods

We conducted a prospective longitudinal observational study at the National Institute of Cardiovascular Diseases (NICVD), Dhaka, from August 2017 through October 2018. The NICVD is the largest public tertiary care cardiac hospital in Bangladesh, managing patients with cardiovascular disorders from throughout the country. Study-appointed physicians reviewed NICVD hospital admission records and visited patients admitted to the cardiology wards to identify potential subjects aged ≥ 18 years hospitalized with a first-onset STEMI. Informed written consent to participate in the study was obtained for collection of extensive baseline and outcome information. The study was approved by the icddr,b institutional review board prior to enrolling participants.

Results

From August 2017 through October 2018, 601 patients, mean age 51.6 [SD\(\pm\) 10.3] years, range 24–80, 93% (559) male, were diagnosed with STEMI based on clinical presentation at admission and electrocardiogram (ECG) findings and included in the study. No patient was lost to follow-up. Baseline data are presented in Table 1. Two-thirds (389/601) of patients had a family history of cardiovascular disease and 25% (148/601) had diabetes mellitus.

Presenting symptoms at hospital are listed in Table 2. An ECG was conducted in all cases. Cardiac troponin I (cTn) was not available for 67% (404/601) of cases; however, among those in which it was assessed, 84% (165/197) showed values above the 99th percentile of the upper reference limit. Significantly higher mean values of cTn were observed in patients who developed MACE during the 30-day follow-up period compared to patients who did not experience MACE (37.3 ng/ml [± SD 43.4] vs. 19.4 ng/ml [±SD 33.7], p = 0.002). Based on ECG/echocardiogram, the most common location of infarct was in the inferior (47%, 283/601) followed by the anterior (27%,165/601) heart wall.

The mean duration of hospital stay was 3.8 (± SD, 2.4) days. Hospitalization of patients who experienced in-hospital MACE was significantly longer than recorded for those who experienced post-discharge 30-day MACE (5.6 days, [± SD 4.5] vs. 3.7 days, [± SD 2.1]; p = 0.022). Thirty-seven (6.2%; 95% CI, 4.2–8.1) in-hospital events included 19 (3.2%) deaths and 18 (3.0%) unplanned revascularization procedures. Within 30 days post-discharge, 45 (7.5%; 95% CI, 5.4–9.6) MACE were recorded, including revascularization procedures (Percutaneous coronary intervention,PCI or Cronary artery bypass grafting, CABG) in 26 (4.3%) patients, 15 deaths (2.5%), and 4 (0.7%) recurrent MIs. Two patients undergoing unplanned revascularization during the hospital stay died during the 30-day follow-up period. In total, 80 MACE occurred during the in-hospital and 30-day follow-up, i.e. 13.3% (80/601) of all patients experienced a MACE (Table 3).

The univariate analysis revealed significantly increased risk of MACE in patients with greater than 12 years of education, diabetes mellitus, or a previous diagnosis of heart failure. We also observed a numerically elevated risk (HR = 1.79; 95% CI, 0.95–3.36) in patients ≥ 65 years, but this did not reach statistical significance. In multivariate analysis, after adjusting for age and education, heart failure (HR = 5.23; 95% CI, 1.83–14.92) remained a significant risk factor for 30-day MACE (Fig. 1).

Discussion

Our prospective study from the largest tertiary cardiac hospital in Bangladesh revealed that 13% of patients admitted with STEMI experienced a MACE within the 30 days post-discharge (Fig. 2). This finding is lower than the 23% MACE within 30 days post-STEMI found in a study in rural Bangladesh [15].

Our 30-day MACE rate following STEMI is much higher compared to reports from the Netherlands (3%), India (5%), and Brazil (10%) [26–28]. The in-hospital MACE rate was lower in our study population compared with results of recent studies from China (12%), Canada (9%), and India (8%) [27, 29, 30]. We were, however, unable to compare our results with regional data because of the paucity of data available of in-hospital MACE in Bangladesh.

Revascularization procedures were the most frequent post-discharge MACE in our study. While most studies report the frequency and predictors of mortality following index MI, especially STEMI [31, 32], focus on rehospitalization and revascularization procedures are warranted, as they consume significant healthcare resources and affect patient quality of life [33, 34]. In our study, no patient underwent primary PCI. This may be because of prolonged symptom onset to hospital arrival time [15]. Revascularization procedures are frequently delayed in Bangladesh, where the majority (67%) of healthcare expenditure is out-of-pocket [35]. Most revascularization procedures are scheduled post-discharge during which time patients and family secure financial resources for the intervention, a practice not compatible with treatment guidelines for acute MI of the European Society of Cardiology [36].

Studies have documented that MACE and mortality after MI is higher in females than in males worldwide, and women are less likely to receive optimal treatment, including post-discharge preventive medication even in high-income settings [2, 37, 38]. A higher rate of MACE and mortality among women has been attributed to biological sex differences and gender differences influenced by social, environmental, and community factors [39, 40]. In a large registry-based study from 125 centres in India, only 22.6% of patients with acute coronary syndrome were female [41]. There were few female patients (7%) in our study. This underrepresentation of females as participants was also a factor in previous studies conducted in Bangladesh and neighboring countries, and represents the known lower risk of cardiovascular disease in women prior to menopause [15, 42–45]. Women tend to show atypical symptoms of acute coronary events and are less likely to present with chest pain [46]. Hence, they are less likely to seek hospital care [47] and optimal treatment [48]. According to the Bangladesh demographic and health survey report of 2014, only 14.1% of women have decision-making capacity with respect to their own healthcare, and three in ten women reported that their husband is the main decision maker for their healthcare [49].

Social and cultural factors may also explain delayed hospitalization or not seeking healthcare. A quarter of our study participants had no formal education, and 41% had education only at the primary level (Table 1). Prevous studies in Bangladesh have documented a low level of education limiting access to healthcare and negatively affecting health care seeking decisions [50, 51].

We found an elevated risk of MACE among patients aged ≥ 65 years that did not reach statistical significance, most likely because of the low numbers of such patients (13%) in our cohort. Nevertheless, increasing age is considered a significant risk factor for mortality after an acute myocardial infarction [52–54]. The choice of treatment for the elderly should be determined by early clinical assessment, time of presentation after STEMI, and underlying comorbidities [55].

We found a statistically significant higher risk of 30-day MACE among patients who had a history of heart failure before the recent STEMI. Heart failure, together with MI, has been considered a major driver of morbidity and mortality. With an established contribution of heart failure to morbidity and mortality after MI, early risk stratification through clinical and laboratory assessment, together with preventative therapeutic strategies, is required to reduce in-hospital and 30-day MACE [56].

Several limitations warrant attention while interpreting our study findings. First, this was a relatively small observational study in a single specialized cardiac hospital in the capital city of Bangladesh, and study results may not generalize to the entire country. Further studies from multiple centers should be undertaken to ascertain rates of MACE after STEMI in larger cohorts. Secondly, the study was not designed to document the type of treatment provided or patient adherence to post-discharge therapy. Thirdly, data of the 30-day follow-up was obtained through phone calls by study physicians with no documented evidence of MACE outcomes to verify responses from patients and or family members. In addition, troponin levels were not available for most partipants. In future studies, review of records of the treatment provided is recommended in determining MACE outcomes. Despite these limitations, this research offers essential information of in-hospital and 30-day MACE after STEMI in Bangladesh.

Conclusions

The study shows a considerable risk of in-hospital and 30-day MACE occurring in patients referred with STEMI in Bangladesh. Our findings highlight the need for resources to provide guideline-recommended treatment for patients with myocardial infarction.

Abbreviations

CABG: Cronary artery bypass grafting

CI: Confidence intervals

cTn: Cardiac troponin I

ECG: Electrocardiogram

HR: Hazard ratio

MACE: Major adverse cardiac events

MI: Myocardial infarction

NICVD: National Institute of Cardiovascular Disease

PCI: Percutaneous coronary intervention

STEMI: ST-segment elevation myocardial infarction

Declarations

Ethics approval and consent to participate: The study was approved by the icddr,b institutional review board prior to enrolling participants, and informed written consent to participate in the study was obtained.

Consent to publish: Not applicable.

Availability of data and materials: Data generated during the study are subject to a data access policy of icddr,b and are available from icddrb’s research administration on reasonable request through the corresponding author.

Competing interests: None of the authors have any financial, personal, or professional relationships to disclose.

Funding: The Swedish International Development Cooperation Agency funded the study. icddr,b is grateful to the Governments of Bangladesh, Canada, Sweden, and the UK for providing core/unrestricted support.

Authors' Contributions: Zubair Akhtar wrote the paper and performed data analysis. Mohammad Abdul Aleem and C Raina MacIntyre conceived the study and carried out with A.K.M. Monwarul Islam and Zubair Akhtar. Probir Kumar Ghosh developed data distribution and visualization. Fahmida Chowdhury and C Raina MacIntyre provided critical feedback. Ole Fröbert provided overall guidance for developing and writing the paper. All authors have read and approved the final manuscript.

Acknowledgments: The authors are grateful to the study data collection team and study participants for their valuable data. We also acknowledge the support of NICVD authority in conducting this study.

References

[1]          A. E. Moran et al., "The global burden of ischemic heart disease in 1990 and 2010: the Global Burden of Disease 2010 study," (in eng), Circulation, vol. 129, no. 14, pp. 1493-501, Apr 8 2014, doi: 10.1161/circulationaha.113.004046.

[2]          D. Mozaffarian et al., "Heart disease and stroke statistics--2015 update: a report from the American Heart Association," (in eng), Circulation, vol. 131, no. 4, pp. e29-322, Jan 27 2015, doi: 10.1161/cir.0000000000000152.

[3]          M. Nichols, N. Townsend, P. Scarborough, and M. Rayner, "Cardiovascular disease in Europe 2014: epidemiological update," (in eng), Eur Heart J, vol. 35, no. 42, p. 2929, Nov 7 2014, doi: 10.1093/eurheartj/ehu378.

[4]          W. J. Rogers et al., "Trends in presenting characteristics and hospital mortality among patients with ST elevation and non-ST elevation myocardial infarction in the National Registry of Myocardial Infarction from 1990 to 2006," American Heart Journal, vol. 156, no. 6, pp. 1026-1034, 2008/12/01/ 2008, doi: https://doi.org/10.1016/j.ahj.2008.07.030.

[5]          P. T. O'Gara et al., "2013 ACCF/AHA guideline for the management of ST-elevation myocardial infarction: a report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines," Journal of the American College of Cardiology, vol. 61, no. 4, pp. e78-e140, 2013.

[6]          R. S. Wright et al., "2011 ACCF/AHA Focused Update of the Guidelines for the Management of Patients With Unstable Angina/Non–ST-Elevation Myocardial Infarction (Updating the 2007 Guideline): A Report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines Developed in Collaboration With the American College of Emergency Physicians, Society for Cardiovascular Angiography and Interventions, and Society of Thoracic Surgeons," Journal of the American College of Cardiology, vol. 57, no. 19, pp. 1920-1959, 2011/05/10/ 2011, doi: https://doi.org/10.1016/j.jacc.2011.02.009.

[7]          B. Spring et al., "Better population health through behavior change in adults: a call to action," (in eng), Circulation, vol. 128, no. 19, pp. 2169-76, Nov 5 2013, doi: 10.1161/01.cir.0000435173.25936.e1.

[8]          B. Vogel et al., "ST-segment elevation myocardial infarction," Nature Reviews Disease Primers, vol. 5, no. 1, p. 39, 2019/06/06 2019, doi: 10.1038/s41572-019-0090-3.

[9]          P. G. Steg et al., "Baseline characteristics, management practices, and in-hospital outcomes of patients hospitalized with acute coronary syndromes in the Global Registry of Acute Coronary Events (GRACE)," (in eng), Am J Cardiol, vol. 90, no. 4, pp. 358-63, Aug 15 2002, doi: 10.1016/s0002-9149(02)02489-x.

[10]        S. Dharma et al., "Organisation of reperfusion therapy for STEMI in a developing country," (in eng), Open Heart, vol. 2, no. 1, p. e000240, 2015, doi: 10.1136/openhrt-2015-000240.

[11]        A. K. M. M. Islam and A. A. S. Majumder, "Coronary artery disease in Bangladesh: A review," Indian Heart Journal, vol. 65, no. 4, pp. 424-435, 2013/07/01/ 2013, doi: https://doi.org/10.1016/j.ihj.2013.06.004.

[12]        K. Smolina, F. L. Wright, M. Rayner, and M. J. Goldacre, "Long-term survival and recurrence after acute myocardial infarction in England, 2004 to 2010," Circulation: Cardiovascular Quality and Outcomes, vol. 5, no. 4, pp. 532-540, 2012.

[13]        T. Jernberg, P. Hasvold, M. Henriksson, H. Hjelm, M. Thuresson, and M. Janzon, "Cardiovascular risk in post-myocardial infarction patients: nationwide real world data demonstrate the importance of a long-term perspective," (in eng), Eur Heart J, vol. 36, no. 19, pp. 1163-70, May 14 2015, doi: 10.1093/eurheartj/ehu505.

[14]        E. Rapsomaniki et al., "Using big data from health records from four countries to evaluate chronic disease outcomes: a study in 114 364 survivors of myocardial infarction," (in eng), Eur Heart J Qual Care Clin Outcomes, vol. 2, no. 3, pp. 172-183, Jul 1 2016, doi: 10.1093/ehjqcco/qcw004.

[15]        D. Y. Kim, Z. Wala, S. Islam, R. Islam, and M. Ahn, "Clinical characteristics and outcomes of ST-segment elevation myocardial infarction in a low income setting in rural Bangladesh," (in eng), Int J Cardiol Heart Vasc, vol. 23, p. 100376, Jun 2019, doi: 10.1016/j.ijcha.2019.100376.

[16]        S. M. Haffner, S. Lehto, T. Rönnemaa, K. Pyörälä, and M. Laakso, "Mortality from coronary heart disease in subjects with type 2 diabetes and in nondiabetic subjects with and without prior myocardial infarction," New England journal of medicine, vol. 339, no. 4, pp. 229-234, 1998.

[17]        S. M. Donahoe et al., "Diabetes and mortality following acute coronary syndromes," Jama, vol. 298, no. 7, pp. 765-775, 2007.

[18]        S. V. Arnold et al., "Predicting adverse outcomes after myocardial infarction among patients with diabetes mellitus," Circulation: Cardiovascular Quality and Outcomes, vol. 9, no. 4, pp. 372-379, 2016.

[19]        Z. Ahsan Karar, N. Alam, and P. Kim Streatfield, "Epidemiological transition in rural Bangladesh, 1986-2006," (in eng), Glob Health Action, vol. 2, Jun 19 2009, doi: 10.3402/gha.v2i0.1904.

[20]        "Global, regional, and national age-sex specific all-cause and cause-specific mortality for 240 causes of death, 1990-2013: a systematic analysis for the Global Burden of Disease Study 2013," (in eng), Lancet, vol. 385, no. 9963, pp. 117-71, Jan 10 2015, doi: 10.1016/s0140-6736(14)61682-2.

[21]        D. S. Alam, M. A. Chowdhury, A. T. Siddiquee, S. Ahmed, and L. W. Niessen, "Awareness and control of hypertension in Bangladesh: follow-up of a hypertensive cohort," (in eng), BMJ Open, vol. 4, no. 12, p. e004983, Dec 23 2014, doi: 10.1136/bmjopen-2014-004983.

[22]        W. H. Organization, "Noncommunicable diseases country profiles 2018," 2018.

[23]        S. J. Reinstadler et al., "Prognostic value of left ventricular global function index in patients after ST-segment elevation myocardial infarction," European Heart Journal - Cardiovascular Imaging, vol. 17, no. 2, pp. 169-176, 2015, doi: 10.1093/ehjci/jev129.

[24]        S. O. Rutstein and K. Johnson, "DHS comparative reports 6: the DHS wealth index," Calverton, MD: ORC Macro, 2004.

[25]        S. Vyas and L. Kumaranayake, "Constructing socio-economic status indices: how to use principal components analysis," Health policy and planning, vol. 21, no. 6, pp. 459-468, 2006.

[26]        N. S. Vos et al., "Prehospital Prasugrel Versus Ticagrelor in Real-World Patients With ST-Elevation Myocardial Infarction Referred for Primary PCI: Procedural and 30-Day Outcomes," (in eng), J Invasive Cardiol, vol. 30, no. 12, pp. 431-436, Dec 2018.

[27]        S. Umapathy, R. Yadav, K. C. Goswami, G. Karthikeyan, N. Parakh, and V. K. Bahl, "Prognostic significance of fragmented QRS in patients with ST-elevation myocardial infarction undergoing revascularization," (in eng), Indian Heart J, vol. 70 Suppl 3, no. Suppl 3, pp. S126-s132, Dec 2018, doi: 10.1016/j.ihj.2018.07.014.

[28]        O. Berwanger et al., "Effect of Loading Dose of Atorvastatin Prior to Planned Percutaneous Coronary Intervention on Major Adverse Cardiovascular Events in Acute Coronary Syndrome: The SECURE-PCI Randomized Clinical Trial," (in eng), Jama, vol. 319, no. 13, pp. 1331-1340, Apr 3 2018, doi: 10.1001/jama.2018.2444.

[29]        R. Liu et al., "Association of thrombocytopenia with in-hospital outcome in patients with acute ST-segment elevated myocardial infarction," (in eng), Platelets, vol. 30, no. 7, pp. 844-853, 2019, doi: 10.1080/09537104.2018.1529298.

[30]        J. Saw et al., "Canadian spontaneous coronary artery dissection cohort study: in-hospital and 30-day outcomes," (in eng), Eur Heart J, vol. 40, no. 15, pp. 1188-1197, Apr 14 2019, doi: 10.1093/eurheartj/ehz007.

[31]        K. A. Eagle et al., "A validated prediction model for all forms of acute coronary syndrome: estimating the risk of 6-month postdischarge death in an international registry," (in eng), Jama, vol. 291, no. 22, pp. 2727-33, Jun 9 2004, doi: 10.1001/jama.291.22.2727.

[32]        E. Boersma et al., "Predictors of outcome in patients with acute coronary syndromes without persistent ST-segment elevation. Results from an international trial of 9461 patients. The PURSUIT Investigators," (in eng), Circulation, vol. 101, no. 22, pp. 2557-67, Jun 6 2000, doi: 10.1161/01.cir.101.22.2557.

[33]        S. V. Arnold, F. A. Masoudi, J. S. Rumsfeld, Y. Li, P. G. Jones, and J. A. Spertus, "Derivation and validation of a risk standardization model for benchmarking hospital performance for health-related quality of life outcomes after acute myocardial infarction," (in eng), Circulation, vol. 129, no. 3, pp. 313-20, Jan 21 2014, doi: 10.1161/circulationaha.113.001773.

[34]        S. V. Arnold et al., "Economic impact of angina after an acute coronary syndrome: insights from the MERLIN-TIMI 36 trial," (in eng), Circ Cardiovasc Qual Outcomes, vol. 2, no. 4, pp. 344-53, Jul 2009, doi: 10.1161/circoutcomes.108.829523.

[35]        A. Mustafa, A. Rahman, N. Hossain, and T. Begum, Bangladesh National Health Accounts 1997-2015 (BNHA-V). 2018.

[36]        B. Ibanez et al., "2017 ESC Guidelines for the management of acute myocardial infarction in patients presenting with ST-segment elevation: The Task Force for the management of acute myocardial infarction in patients presenting with ST-segment elevation of the European Society of Cardiology (ESC)," European heart journal, vol. 39, no. 2, pp. 119-177, 2018.

[37]        "Correction," (in eng), Circulation, vol. 131, no. 24, p. e535, Jun 16 2015, doi: 10.1161/cir.0000000000000219.

[38]        E. Khan et al., "Differences in management and outcomes for men and women with ST-elevation myocardial infarction," (in eng), Med J Aust, vol. 209, no. 3, pp. 118-123, Aug 6 2018.

[39]        S. Institute of Medicine Committee on Understanding the Biology of and D. Gender, "The National Academies Collection: Reports funded by National Institutes of Health," in Exploring the Biological Contributions to Human Health: Does Sex Matter?, T. M. Wizemann and M. L. Pardue Eds. Washington (DC): National Academies Press (US)

Copyright 2001 by the National Academy of Sciences. All rights reserved., 2001.

[40]        R. Institute of Medicine Committee on Women's Health, in Women’s Health Research: Progress, Pitfalls, and Promise. Washington (DC): National Academies Press (US)

Copyright 2010 by the National Academy of Sciences. All rights reserved., 2010.

[41]        P. P. Mohanan et al., "Presentation, management, and outcomes of 25 748 acute coronary syndrome admissions in Kerala, India: results from the Kerala ACS Registry," (in eng), Eur Heart J, vol. 34, no. 2, pp. 121-9, Jan 2013, doi: 10.1093/eurheartj/ehs219.

[42]        M. A. Karim et al., "Risk factors and in-hospital outcome of acute ST segment elevation myocardial infarction in young Bangladeshi adults," (in eng), BMC Cardiovasc Disord, vol. 15, p. 73, Jul 22 2015, doi: 10.1186/s12872-015-0069-2.

[43]        S. S. Roy, S. T. M. Abu Azam, M. Khalequzzaman, M. Ullah, and M. Arifur Rahman, "GRACE and TIMI risk scores in predicting the angiographic severity of non-ST elevation acute coronary syndrome," (in eng), Indian Heart J, vol. 70 Suppl 3, no. Suppl 3, pp. S250-s253, Dec 2018, doi: 10.1016/j.ihj.2018.01.026.

[44]        N. R. Shreshta et al., "Presentation and outcome of patients with acute coronary syndromes in eastern Nepal," (in eng), Swiss Med Wkly, vol. 141, p. w13174, 2011, doi: 10.4414/smw.2011.13174.

[45]        D. Prabhakaran, P. Jeemon, and A. Roy, "Cardiovascular Diseases in India: Current Epidemiology and Future Directions," (in eng), Circulation, vol. 133, no. 16, pp. 1605-20, Apr 19 2016, doi: 10.1161/circulationaha.114.008729.

[46]        G. Graham, "Acute Coronary Syndromes in Women: Recent Treatment Trends and Outcomes," (in eng), Clin Med Insights Cardiol, vol. 10, pp. 1-10, 2016, doi: 10.4137/cmc.S37145.

[47]        J. A. Singh, X. Lu, S. Ibrahim, and P. Cram, "Trends in and disparities for acute myocardial infarction: an analysis of Medicare claims data from 1992 to 2010," (in eng), BMC Med, vol. 12, p. 190, Oct 24 2014, doi: 10.1186/s12916-014-0190-6.

[48]        H. L. Nguyen, J. S. Saczynski, J. M. Gore, and R. J. Goldberg, "Age and sex differences in duration of prehospital delay in patients with acute myocardial infarction: a systematic review," (in eng), Circ Cardiovasc Qual Outcomes, vol. 3, no. 1, pp. 82-92, Jan 2010, doi: 10.1161/circoutcomes.109.884361.

[49]        N. I. o. P. Research, Training, Mitra, Associates, and I. International, "Bangladesh demographic and health survey 2014," ed: NIPORT, Mitra and Associates, and ICF International Dhaka, Bangladesh, and …, 2016.

[50]        J. D. Parr, W. Lindeboom, M. A. Khanam, and T. L. Pérez Koehlmoos, "Diagnosis of chronic conditions with modifiable lifestyle risk factors in selected urban and rural areas of Bangladesh and sociodemographic variability therein," BMC Health Services Research, vol. 11, no. 1, p. 309, 2011/11/11 2011, doi: 10.1186/1472-6963-11-309.

[51]        F. B. Rasul et al., "Determinants of health seeking behavior for chronic non-communicable diseases and related out-of-pocket expenditure: results from a cross-sectional survey in northern Bangladesh," Journal of Health, Population and Nutrition, vol. 38, no. 1, p. 48, 2019/12/23 2019, doi: 10.1186/s41043-019-0195-z.

[52]        R. M. Isaksson, J. H. Jansson, D. Lundblad, U. Näslund, K. Zingmark, and M. Eliasson, "Better long-term survival in young and middle-aged women than in men after a first myocardial infarction between 1985 and 2006. An analysis of 8630 patients in the northern Sweden MONICA study," (in eng), BMC Cardiovasc Disord, vol. 11, p. 1, Jan 5 2011, doi: 10.1186/1471-2261-11-1.

[53]        E. Rapsomaniki et al., "Prognostic models for stable coronary artery disease based on electronic health record cohort of 102 023 patients," (in eng), Eur Heart J, vol. 35, no. 13, pp. 844-52, Apr 2014, doi: 10.1093/eurheartj/eht533.

[54]        R. Nakazato et al., "Age-related risk of major adverse cardiac event risk and coronary artery disease extent and severity by coronary CT angiography: results from 15 187 patients from the International Multisite CONFIRM Study," (in eng), Eur Heart J Cardiovasc Imaging, vol. 15, no. 5, pp. 586-594, 2014, doi: 10.1093/ehjci/jet132.

[55]        A. Carro and J. C. Kaski, "Myocardial infarction in the elderly," (in eng), Aging Dis, vol. 2, no. 2, pp. 116-137, 2011. [Online]. Available: https://pubmed.ncbi.nlm.nih.gov/22396870

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3295051/.

[56]        T. J. Cahill and R. K. Kharbanda, "Heart failure after myocardial infarction in the era of primary percutaneous coronary intervention: Mechanisms, incidence and identification of patients at risk," (in eng), World J Cardiol, vol. 9, no. 5, pp. 407-415, May 26 2017, doi: 10.4330/wjc.v9.i5.407.